A circuit module in which a periphery of a mounting component mounted on a circuit substrate is sealed by a sealing body formed of a synthetic resin or the like is used. Here, when the mounting component is a wireless communication device, for example, a surface of the sealing body is covered with a conductive body that is to be used as a shield against a failure due to electromagnetic waves (hereinafter, referred to as electromagnetic failure). Examples of the electromagnetic failure include an interference and an unnecessary radiation. By providing the shield, an electromagnetic failure with respect to an electronic apparatus outside the shield, that is due to electromagnetic waves generated from a mounting component inside the shield, is prevented from occurring (emission improvement), and an electromagnetic failure due to electromagnetic waves from outside the shield with respect to a mounting component inside the shield is prevented from occurring (immunity improvement).
Further, a circuit module in which a shield is provided to separate, when a plurality of mounting components are mounted on a circuit substrate, the mounting components from one another for preventing an electromagnetic failure from occurring among the mounting components is being developed. Since the mounting components are covered by the sealing body as described above, the shield provided among the mounting components can be formed by partially removing the sealing body to form a trench (groove) and forming a conductive body inside the trench. The conductive body can be formed by, for example, filling a conductive resin paste inside the trench.
For example, Patent Document 1 discloses a circuit module in which a shield among electronic components is formed by forming a slit on a mold resin layer and filling a conductive resin inside the slit.
Patent Document 1: Japanese Patent Application Laid-open No. 2010-225620